Subtraction key latch



I-ay 24 l932- o. J.' suNDsrRAND 1,859,897

SUBTRACTYION KEY LATCH Filed Jan. 14. 1929 l Il' Z l'Patented May 24, 19,32

UNITED STATES PATENT oFFicE OSCAR Il'. SUNDSTRAND, OF ROCKFORD, ILLINOIS, ASSIGNOR TO SUNDSTRAND CORPO- RATION, F WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE SUBTRACTION KEY LATCH Application led January 14, 1929. Serial No. 332,460.

This invention relates to adding and subtgacting machines. narily comprises a subtraction key by means of which the machine is conditioned for the subtraction of items. I have herein shown vthe invention as embodied in a machine of the Sandstrand type, as shown, for example, in my application Serial No. 118,628, filed June 26 1926. In that machine means is provided for automatically conditioning the machine for the taking of a credit total, de-

pression of the subtraction key for that pur* pose being unnecessary.

It is. desirable to be able to latch the subtraction key depressed when a number of items are to be subtracted in succession, but it should not be possible to take a total While the subtraction ke'y is depressed, as in that event the amount lprinted as the total would be incorrect if the total accumulated in the counter were a debit. s

The object of the present invention is to provide improved means to prevent the taking of a total while the Subtraction key is depressed.

In the accompanying drawings, Figure 1 is a fragmental plan view of a mechanism embodying my invention.

`F ig. 2 is a fragment-al elevation.

. Fig. 3 is a view showing the subtraction key latched down.

The subtraction key 1 is carried by a stem 2 Which is guided for verticalmovement. spring 3 normally holds the key elevated. The stem 2 carries a pin 4 that overlies an arm 5 which is pivoted at 6. Rigid with the arm 5 is an arm 7 to which pivotcd a link 8 that constitutes part of the means for conditioning ythe machine for the subtraction of items and the taking of credit totals.

In order that the subtraction key may be latched down when a succession ot items are to be subtracted, I provide on the stem ot the subtraction key a latch 9 which is pivoted at 10 and has a handle 11. The lat-ch 9 may be swung' to place the shoulder 12 thereof beneath a stationary projection 13.

In order to prevent a total from being` taken ivhile the subtraction key is latched down, I provide an arm 14 pivoted at l5, the

Such a machine ord1` arm 17 which carries a pin 18 that underlies a cam arm 19 fixed on a transverse rock shaft 20. Rigidly connected to the left-hand end of the shaft 20 is an arm 21 which is piv oted to a slide 22. The rear portion of the slide 22 is supported on a stud 23 carried by the machine frame. A finger 24 is pivoted to the rear end of the slide 22 at 25. A spring 26 normally holds the finger 24 with the stop lug 27 thereof against a pin 28 on the slide 22. The finger 24 operates a means for controlling the taking of totals. In the construction chosen for illustration herein, the finger 24 bears against a pivoted member 300, the construction and function of which are fully described in my Patent No. 1,583,102. In the present instance it will be suiiicient to note that the member 300 and its associated elements operate to obstruct movement of the type bars and racks during the ensuing cycle of operations of the machine, thus producing a blank or spacing stroke. As will be understood byreference to said patent, the finger 24 is yieldingly mounted on the slide 22 so that if the main operating handle should be pulled While the subtraction key is depressed, the member 300 may swing forward. On the return stroke'of the handle the spring 26 operating upon the finger 24 pushes the member 800 into the total- A preventing position.

When the operator unlatches the subtraction key 1, the spring 3 raises the key to its normal position. VIn the operation of taking a total, as described in said Patent No. 1,588,102, the member is pushed forward, there-by restoring the slide 22 and the arm 14 to normal position.

Various changes may be made Without departing Jfrom the spirit and scope of the invention as indicated in the appended claims.

I claim as my invention:

1. In an adding and subtracting machine, the combination of a subtraction key, a pivoted arm arranged to be moved by said key, an arm rigid with the first arm, a cam arm arranged to be moved by the second arm, a transverse rock shaft on one end of which 2 i 1,aso,esv

said cam arm is fixed, a longitudinally mov- 'able slide arranged to be moved by the rock shaft, a finger yieldingiy mounted on the rear end of the slide, and means to prevent 5 the taking of a total, said inger being arranged vto actuate said preventing means in the rearward movement of the slide.

2.r In an adding and subtraetin machine, the combination of a subtraction ey, a pivoted arm arranged to be moved by said key, an arm rigid with the first arm, a cam arm arranged to be moved by the second arm, a slide arranged to be moved by the cam arm, a finger yieldingiy mounted on the slide, and

means to prevent the taking of a total, said finger being arranged to aotuate Said preventing means. v

3. In an addingand subtracting machine,

. thevcombination of a'fsubtraetion key, a pivoted arm arranged to be moved by said key, a slide arranged to bmoved by the arm, a finger yieidingly mounted on the siide, and means to prevent the taking of a total, said finger being arranged to actuate said preventing means.

4. In an adding and subtracting machine., the combination of a subtraction key, a slide arranged to be moved by the key, a finger yieldingly mounted on the slide, and means to prevent tbe taking of a total, said finger being arranged to actuate said preventing means.

In testimony whereof, I have hereunto aiixed my signature. s

OSCAR J. SUNDSTRANI). 

